1. Field of the Invention
This invention relates to a self-luminescent light source which makes the night display of a liquid crystal display watch.
2. Description of the Prior Art
A liquid crystal display watch displays letters and numerals by reflecting external light. Accordingly, the display is impossible in a dark place or in the nighttime.
In order to overcome the drawback, the night display has heretofore been effected by inserting at the back of a liquid crystal display element a tubular self-luminescent light source whose inner wall is coated with a fluorescent material and in which high-pressure tritium gas (.sup.3 H) is contained. However, in order to obtain a light source which is bright enough to recognize the numerals of a liquid crystal with the eyes, its radioactive intensity must be on the order of 100 mC.sub.i, which is not always desirable from the aspect of safety.